Hybrid ceramic bearing-equipped bottom brackets are widespread at this point but few have been as silky smooth and friction-free straight out of the box as the Enduro ZERØ. When compared to some of the more drag-prone stock units out there, the difference on the road is akin to using a chain that's properly oiled instead of bone dry and it's no surprise that some top-level pros have even shelled out their own money in the past to make sure they're properly equipped (and we have copies of the receipt to prove it).
Don't believe us? Fair enough. Though we didn't take this particular unit into the lab, earlier tests done on a slightly more expensive FSA MegaExo Ceramic bottom bracket at an independent facility verified a 3.5 percent reduction in drivetrain friction and that advantage would only grow with increasing pedal load (conventional steel bearing compress more easily under load than ceramics). Whether or not you can tell a difference on the bike is neither here nor there – the numbers don't lie.
Installation is just as straightforward as any standard bottom bracket and construction quality is also top notch. Enduro builds the cartridges with its highest quality Grade 3 silicon nitride bearings, hardened 'Magnetite' chromium steel races, graphite-infused nylon retainers to prevent the bearings from rubbing against each other, and low-friction silicone lip seals. Moreover, the machined and anodised cups, central sleeve, and bearing shields lend an obvious precision fit to the whole assembly.
Enduro recommends the ZERØ only for road use, though, as part of its low-friction performance comes from its minimal sealing. As the outer shields offer no contact seals whatsoever – only a tight fit against the surrounding cup – the only true barriers against water are the lip seals on the bearing cartridges. We've had no issues after nearly a year of use (including an extended stint off-road, albeit in mostly dry conditions) but use it on your mountain bike at your own risk.
Pros: Fantastically fast and smooth feel underfoot, light weight, reasonable cost, high quality machined aluminium construction
Cons: Minimal sealing likely won't hold up long-term to persistent water exposure, only recommended for road applications, only available in red and blue, no Italian thread option.